1. Field of the Invention
This invention generally relates to a device and a method for equalizing pressure between an internal space in an endoscope and an environment about the endoscope.
2. Description of the Related Art
In modern medical practices, it has been a common practice to sterilize instruments used for medical or surgical purposes before each use. It is important that the sterilization and cleaning of such instruments be performed efficiently and quickly without damaging the materials or functionality of the device. However, the ever increasing complexity of such instruments requires corresponding modifications in conventional cleaning and sterilization equipment and processes, which makes the sterilization and cleaning related problems one of the critical aspects of using such instruments.
This is particularly relevant to instruments comprising elongated channels, such as endoscopes. A typical endoscope generally includes two elongated tubular bodies having a distal portion and a proximal portion. The distal portion of the endoscope is generally flexible enough to be inserted into a human body or animal body, and is often referred to in the art as an insertion tube. The endoscope usually contains various internal components, such as wires, for controlling movements of the endoscope as well as a number of tubular passages for passing air, liquid or instruments. In addition, endoscopes are furnished with an image transmission means, such as fiber optic cables, or CCD camera with electrical cables, to transmit images from a distal location in a body.
Such components are conveniently sealed and protected in an internal space of the endoscope by a gas and liquid tight sheath. This sheath is generally made of an elastomeric material and surrounds the endoscope. After each use, it is important that the interior surface of the tubular passages, along with the surrounding sheath, be carefully cleaned and sterilized for reasons of sanitation. At present, some conventional sterilization processes utilize sterilant gas, such as hydrogen peroxide or ethylene oxide, in low pressure sterilization chambers to sterilize endoscopes. However, in such sterilization processes, as the pressure is lowered, the air trapped at the internal space of the endoscope exerts pressure against the elastomeric sheath. If this pressure at the internal space is not properly released, the elastomeric sheath may rupture with the high pressure. In fact, typical prior art endoscopes use a sealable port for releasing the entrapped air during any reduced pressure sterilization process. During a sterilization process in a reduced pressure environment, a cap sealing this sealable port may be opened to allow the internal space of the endoscope to communicate with the sterilizing atmosphere so that the excess pressure within the endoscope may be relieved. However, this port needs to be closed during the washing procedures of the exterior of the endoscope to prevent the flow of cleaning liquid into the endoscope. Therefore, an operator has to either close or open the sealing cap, depending on the type of treatment.
Unfortunately, this situation presents a special challenge for newer in-situ sterilization processes which use liquid sterilant at atmospheric pressure and vapor sterilants in reduced pressure in a continuous cycle. In such systems, briefly, a liquid sterilant, such as liquid hydrogen peroxide, is initially delivered to a sterilization chamber containing articles to be sterilized so that these articles can be pretreated with the liquid sterilant. Subsequently, the liquid sterilant is vaporized in the chamber using vacuum so that the articles are exposed to the sterilant vapor. It will be appreciated, however, that it is very difficult to design a mechanical system which can sequentially close and open this port in the chamber as the sterilization cycle advances from the liquid treatment stage to the reduced pressure vapor sterilization stage.
Therefore, there is a need for alternative systems which allow cleaning and sterilization of endoscopes in the sterilization processes using liquid and vapor sterilants in a continuous cycle in a sterilization chamber.